MySQL SQL - 如何在选择中隐藏列
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SQL - How to hide column in select
提问by Black
I have two tables "contract" and "worker". I need to find the worker which has the most holidays left. However, I only need to print his name, not the holidays.
我有两个表“合同”和“工人”。我需要找到剩余假期最多的工人。但是，我只需要打印他的名字，而不是假期。
SCHEMA
架构
Contract:
合同：
Contract_ID (PK)
Worker_ID (FK)
holidays
Worker
工人
Worker_ID (PK)
Name
SAMPLE DATA:
样本数据：
contract
合同
worker
工人
CODE
代码
Currently I print the information out with this code:
目前我用以下代码打印信息：
EDIT: The following SQL Code is wrong! It shows Fegeleineven though Klinkis the person with the most holidays.
编辑：以下 SQL 代码是错误的！它显示Fegelein即使Klink是假期最多的人。
SELECT W.Name, MAX(C.Holidays) As Holidays
FROM worker AS W, contract AS C
WHERE W.Worker_ID = C.Worker_ID
Result:
结果：
Name Holidays
Fegelein 31
Desired Result:
预期结果：
Name
Fegelein
SQL Fiddle: http://sqlfiddle.com/#!9/a840b/17
SQL小提琴：http: //sqlfiddle.com/#!9/a840b/17
So I need to hide the second select MAX(C.Holidays) As Holidays. Is this possible?
所以我需要隐藏第二个 select MAX(C.Holidays) As Holidays。这可能吗？
回答by Gordon Linoff
Neveruse commas in the FROMclause. Alwaysuse proper, explicit JOINsyntax. Or, as a comment I saw yesterday suggests . . . JOINthe modern world.
切勿在FROM子句中使用逗号。 始终使用正确、明确的JOIN语法。或者，正如我昨天看到的评论所暗示的那样。. . JOIN现代世界。
If you only want one such worker, then use LIMIT:
如果你只想要一个这样的工人，那么使用LIMIT：
SELECT w.Name
FROM worker w JOIN
contract c
ON w.Worker_ID = c.Worker_ID
ORDER BY c.Holidays DESC
LIMIT 1;
Mostholidays appears to be the smallest value of holiday. If it is the smallest value (as suggested by your question), use ORDER BY c.Holidays ASC.
大多数假期似乎是 的最小值holiday。如果它是最小值（如您的问题所建议的那样），请使用ORDER BY c.Holidays ASC.
Presumably, workers might be on multiple contracts, so you might want aggregation. However, that is unclear.
据推测，工人可能有多个合同，因此您可能需要聚合。然而，这还不清楚。
Hereis a SQL Fiddle.
这是一个 SQL 小提琴。
回答by Sanchit Gupta
Simply try with :
只需尝试：
SELECT w.Name
FROM worker w JOIN
contract c
ON w.Worker_ID = c.Worker_ID
ORDER BY c.Holidays DESC
You can add LIMIT 1if you need only one result.
LIMIT 1如果您只需要一个结果，您可以添加。
回答by Web Artisan
I think this should do your job.
我认为这应该可以完成您的工作。
SELECT W.Name
FROM worker AS W, contract AS C
where W.Worker_ID = C.Worker_ID order by C.Holidays limit 1;
Delete Holidays from select attributes and limit it to 1 and orderby Holidays does the job
从选择属性中删除 Holidays 并将其限制为 1 并且 orderby Holidays 完成这项工作
